That's exactly what the Greek says. The adjective "last" is used to modify the noun "trumpet", not the verb.
Check out the Greek and see for yourself.
Whether you call it a trumpet or a trump, makes no difference as long as you know what's being discussed...
We're talking about the 'last' of the sounds being trumpeted...
1Co 15:52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
The trump, the 'sound' will be the last sound heard...
The trumpet in this verse is a verb which combined with the others in the group are as follows...
G4537
σαλπίζω
salpizō
sal-pid'-zo
From G4536; to trumpet, that is, sound a blast (literally or figuratively): - (which are yet to) sound (a trumpet).
So to summarize, in the GREEK, you get this:
1Co 15:52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
This has nothing to with your idea of the 'last trumpet will sound'...
Trumpet in the New Testament has little to do with the Hebrew translated trumpet of the Old Testament...There commonality is of producing a loud sound...None of the Angels in Revelation are blowing tuba's or French horns...
In Revelation the emphasis is on the Angels and their number and then the sound they are making...
Rev 10:7 But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as he hath declared to his servants the prophets.
AND
Rev 11:15 And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign forever and ever.
There's the seventh 'trumpet'...And for those of you who somehow reject the Millenial reign of Jesus Christ, you can see the kindgoms of THIS world become the kingdoms of our Lord...Jesus will reign on earth for a thousand years...